This invention relates generally to Bit Rate Agile (BRA) signal processors; more particularly to cross-correlated signal processors for increasing RF spectral and power efficiency of modulated transmitted signals including but not limited to digital binary, digital multilevel, and/or analog modulated signals operated in linearized and in power-efficient Non-Linearly Amplified (NLA) systems; and most particularly to BRA and RF Agile Cascaded Time Constrained Signal (TCS) response and Long Response (LR) filtered and Mis-Matched (MM) filtered (ACM) quadrature phase, frequency and amplitude modulated Transmitter, Receiver, and Transceiver systems having these characteristics and methods and procedures provided thereby.
The most important objectives of wireless communications, broadcasting, telemetry, infrared and in general xe2x80x9cradioxe2x80x9d systems as well as xe2x80x9cwiredxe2x80x9d systems include: power and bandwidth or spectrum efficiency combined with robust Bit Error Rate (BER) performance in a noisy and/or strong interference environment. These system objectives are specified in numerous systems including wireless communications and cellular systems, satellite systems, mobile and telemetry systems, broadcasting systems, cable, fiber optics and practically all communication transmission systems. A partial list of publications, references, and patents are provided separately below. The cited publications, references [1-23] and patents [P1-P8], and the references within the aforementioned publications contain definitions and descriptions of many terms used in this new patent disclosure and for this reason these conventional terms and definitions will be described only briefly, and highlighted on a case by case basis.
Robust or high performance Bit Error Rate (BER) specifications and/or objectives are frequently expressed in terms of the required BER as a function of Energy per Bit (Eb) divided by Noise Density or simply noise (No), that is, by the BER=f (Eb/No) expression. Low cost, reduced size, and compatibility and/or interoperability with other conventional or previously standardized systems, also known as xe2x80x9clegacy systems,xe2x80x9d are highly desired. Several standardization organizations have adopted modulation techniques such as conventional Binary Phase Shift Keying (BPSK), Quadrature Phase Shift Keying (QPSK), Offset Quadrature Phase Shift Keying (OQPSK) also designated as Staggered Quadrature Phase Shift Keying (SQPSK), and pi/4-QPSK (or xcfx80/4-QPSK) techniques including differential encoding variations of the same. See publications [1-23] and referenced patents [P1-P8] for examples and further description. For spectrally or spectrum efficient signaling (such as band-limited signaling), these conventional methods exhibit a large envelope fluctuation of the modulated signal, and thus have a large increase in peak radiated power relative to the average radiated power. For these reasons such systems are not suitable for BRA, robust BER performance NLA operated RF power efficient systems.
Within the present state of the technology, for numerous BRA Transceiver applications, it is not practical to introduce band-pass filtering after the NLA power efficient Radio Frequency (RF) final amplifier stage. Here we are using the term xe2x80x9cRadio Frequencyxe2x80x9d (RF) in its broadest sense, implying that we are dealing with a modulated signal. The RF could be, for example, as high as the frequency of infrared or fiber optic transmitters; it could be in the GHz range, for example, between 1 GHz and 300 GHz or more, or it could be in the MHz range, for example, between about 1 MHz and 999 MHz, or just in the kHz range. The term RF could even apply to Quadrature Modulated (abbreviated xe2x80x9cQMxe2x80x9d or xe2x80x9cQMODxe2x80x9d) Base-Band (BB) signals or to Intermediate Frequency (IF) signals.
In conventional BPSK, QPSK, OQPSK or SQPSK, and differentially-encoded phase-shift keying systems variants of these systems, such as DBPSK and DQPSK, as well as in pi/4-DQPSK and trellis coded QPSK and DQPSK, large envelope fluctuations require linearized (LIN) or highly linear transmitters including frequency up-converters and RF power amplifiers and may require expensive linear receivers having linear Automatic Gain Control (AGC) circuits. A transmitter NLA reduces the time domain envelope fluctuation of conventional QPSK type of band-limited signals and this reduction of the envelope fluctuation, being a signal distortion, is the cause of spectral restoration or spectral regrowth and the cause of unacceptably high levels of out-of-band spectral energy transmission, also known as out-of-band interference. Additionally, for conventional BPSK, QPSK, and also Quadrature Amplitude Modulation number (QAM) signals, undesired inphase channel (I) to quadrature channel (Q) crosstalk is generated. This crosstalk degrades the BER=f(Eb/No) performance of the modulated radio transmitter.
Experimental work, computer simulation, and theory documented in many recent publications indicates that for band-limited and standardized BPSK, QPSK, OQPSK or SQPSK or pi/4-QPSK, and QAM system specifications, very linear amplifiers are required to avoid the pitfalls of spectral restoration and of BER degradation. Linearized or linear amplifiers are less RF power efficient (during the power xe2x80x9conxe2x80x9d state, power efficiency being defined as the transmit RF power divided by DC power), are considerably more expensive and/or having less transmit RF power capability, are larger in size, and are not as readily available as NLA amplifiers. The advantages of NLA over LIN amplifiers are even more dramatic at higher RF frequencies, such as frequencies above about 1 GHz for applications requiring low dc voltage, for example applications or systems operating on size xe2x80x9cAAxe2x80x9d batteries having only 1.5 Volt dc and for high RF modulated power requirements, for example transmit RF power in the 0.5 Watt to 100 Watt range.
Published references [P1 to P8] and [1 to 23] include additional background information. These references include descriptions of binary-state and multiple-state Transmitter/Receiver (Transceiver) or for short (xe2x80x9cTRxe2x80x9d) systems that are suitable for NLA. In the aforementioned references Processors, Modems, Transmitters, Receivers and Transceivers, suitable for NLA, have been described, defined and designated as first generation of Feher patented Quadrature Shift Keying (FQPSK). For example, in reference [22] published on May 15, 1999 the authors Drs. M. K. Simon and T. Y. Yan of JPL/NASA-Caltech present a detailed study of Unfiltered Feher-Patented Quadrature Phase Shift Keying (FQPSK). In references [1xe2x80x9422] and patents #[P1-P8] numerous first generation FQPSK technology based terms, and terms other than the FQPSK abbreviation/acronym have been used. In addition to FQPSK Transceivers, these first generation of systems have been also described and/or defined as: Feher""s Minimum Shift Keying (FMSK), Feher""s Frequency Shift Keying (FFSK), Feher""s Gaussian Minimum Shift Keying (FGMSK), Feher""s Quadrature Amplitude Modulation (FQAM) and/or Feher""s (F) Modulation/Amplification (FMOD). Additionally terms such as Superposed Quadrature Amplitude Modulation (SQAM), Intersymbol Interference and Jitter Free (IJF) and/or IJF-OQPSK have been also described in Feher et al.""s prior patents and publications, each of which is incorporated by reference.
In the cited patents and other references, among the aforementioned abbreviations, acronyms, designation, terms and descriptions the xe2x80x9cFQPSKxe2x80x9d abbreviation/term has been most frequently used to describe in most generic terms one or more of these afore described Feher or Feher et al. first generation of Non-Linearly Amplified (NLA) inventions and technologies. The 1st generation of FQPSK systems have significantly increased spectral efficiency and enhanced end-to-end performance as compared to other NLA systems. RF power advantages, robust BER performance, and NLA narrow spectrum without the pitfalls of conventional BPSK and DBPSK, QPSK and OQPSK have been attained with these 1st generation FQPSK systems and methods. The generic 1st generation terms such as FQPSK, as well as other previously mentioned terms/acronyms are retained and used in this description to describe the new BRA, Code Selectable (CS), Modem Format Selectable (MFS) and modulation-demodulation Mis-Matched (MM) filtered architectures and embodiments of xe2x80x9c2nd generationxe2x80x9d FQPSK Transceivers.
While these earlier issued patents and publications describe material of a background nature, they do not disclose the original new enhanced performance bit rate agile and modulation agile/selectable technologies disclosed in this new invention.
Several references, including U.S. Patents, International or Foreign Patents, publications, conferences proceedings, and other references are identified herein to assist the reader in understanding the context in which the invention is made, some of the distinctions of the inventive structures and methods over that which was known prior to the invention, and advantages over the invention. No representation is made as to whether the contents of the cited references represent prior-art as several of the cited references have a date after the effective filing date (priority date) of this patent application. This list is intended to be illustrative rather than exhaustive.
U.S. Patents
[P1] U.S. Pat. No. 5,784,402 Issued July 1998 to Feher
[P2] U.S. Pat. No. 5,491,457 Issued February 1996 to Feher
[P3] U.S. Pat. No. 4,720,839 Issued January 1988 to Feher et al.
[P4] U.S. Pat. No. 4,644,565 Issued February 1987 to Seo/Feher
[P5] U.S. Pat. No. 4,567,602 Issued January 1986 to Kato/Feher
[P6] U.S. Pat. No. 4,350,379 Issued September 1982 to Feher
[P7] U.S. Pat. No. 4,339,724 Issued July 1982 to Feher
[P8] U.S. Pat. No. 3,954,926 Issued March 1976 to Feher
Foreign Patent Documents:
[PF1] Canadian Patent No. 1130871 August 1982
[PF2] Canadian Patent No. 1211517 September 1986
[PF3] Canadian Patent No. 1265851 February 1990
Other Publications:
1. Feher, K.: Wireless Digital Communications: Modulation Spread Spectrum. Prentice Hall, 1995.
2. Feher, K.: Digital Communications: Satellite/Earth Station Engineering. Prentice Hall, 1983. Available from Crestone Engineeringxe2x80x94Noble Publishing, 2245 Dillard Street, Tucker, Ga. 30084.
3. Feher, K.: Advanced Digital Communications. Systems and Signal Processing. Prentice Hall, 1987. Available from Crestone Engineeringxe2x80x94Noble Publishing, 2245 Dillard Street, Tucker, Ga. 30084.
4. Feher, K.: Digital Communications: Microwave Applications. Prentice Hall 1981. Since 1997 available from Crestone Engineeringxe2x80x94Noble Publishing, 2245 Dillard Street, Tucker, Ga. 30084.
5. Feher, K. and Engineers of Hewlett-Packard: Telecommunications Measurements, Analysis, and Instrumentation: Prentice Hall 1987 Since 1997 reprints have been available from Crestone Engineeringxe2x80x94Noble Publishing, 2245 Dillard Street, Tucker, Ga. 30084.
6. Feher, K., Emmenegger, H.: xe2x80x9cFQPSK Use for Electronic News Gathering (ENG), Telemetry and Broadcasting,xe2x80x9d Proc. of the National Association of Broadcasters NAB""99 Broadcast Engineering Conference, Las Vegas, Apr. 19-22, 1999.
7. Feher, K.: xe2x80x9cFQPSK Doubles Spectral Efficiency of Operational Systems: Advances, Applications, Laboratory and Initial Air-to-Ground Flight Testsxe2x80x9d (Date of Submission: Aug. 14, 1998). Proc. of the International Telemetry Conference, ITC-98 ITC/USA 98, San Diego, Calif., Oct. 26-29, 1998.
8. W. Gao, S. H. Wang, K. Feher: xe2x80x9cBlind Equalization for FQPSK and FQAM Systems in Multipath Frequency Selective Fading Channels,xe2x80x9d Proc. Internat. Telemetry Conf. ITC/USA""99, Oct. 25-28, 1999, Las Vegas, Nev.
9. Terziev, G., Feher, K.: xe2x80x9cAdaptive Fast Blind Feher Equalizers (FE) for FQPSK,xe2x80x9d Proc. Of the International Telemetry Conference ITC/USA""99, Oct. 25-28, 1999, Las Vegas, Nev.
10. Feher, K.: xe2x80x9cFQPSK Transceivers Double the Spectral Efficiency of Wireless and Telemetry Systemsxe2x80x9d Applied Microwave and Wireless Journal, June 1998.
11. Seo, J-S. and K. Feher: xe2x80x9cBandwidth Compressive 16-State SQAM Modems through Saturated Amplifiers,xe2x80x9d IEEE Radio Commun., ICC ""86, Toronto, June 1986.
12. Kato, S. and K. Feher: xe2x80x9cXPSK: A new cross-correlated PSK,xe2x80x9d IEEE Trans. Com., May 1983.
13. Law, E. L., U.S. Navy: xe2x80x9cRobust Bandwidth Efficient Modulationxe2x80x9d European Telemetry Conference, ETC-98, Germany, May 1998.
14. Feher, K.: xe2x80x9cFQPSK Doubles the Spectral Efficiency. of Operational Telemetry Systems,xe2x80x9d European Telemetry Conference, ETC-98, May 1998, Germany.
15. Do, G. and K. Feher: xe2x80x9cFQPSK-GMSK: Wireless System Tests an ACI Environment, xe2x80x9d Proc. of Wireless Symposium, Santa Clara, Calif., Feb. 9-13, 1998.
16. Law, E. and K. Feher: xe2x80x9cFQPSK versus PCM/FM for Aeronautical Telemetry Applications: Spectral Occupancy and Bit Error Probability Comparisonsxe2x80x9d Proc. of ITC-97, Las Vegas, October 1997.
17. Feher, K xe2x80x9cFQPSK Doubles Spectral Efficiency of Telemetry: Advances and Initial Air to Ground Flight Tests,xe2x80x9d ITC/USA 98, Proc. of the Internat. Telemetry Conference, San Diego, October 1998.
18. Law, E. and K. Feher: xe2x80x9cFQPSK versus PCM/FM for Aeronautical Telemetry Applications; Spectral Occupancy and Bit Error Probability Comparisons,xe2x80x9d Proc. of the Internat. Telemetry Conf., Las Vegas, Nev., Oct. 27-30, 1997.
19. Martin, W. L., T-Y. Yan, L. V. Lam: xe2x80x9cEfficient Modulation Study at NASA/JPL,xe2x80x9d Proc. of the Tracking, Telemetry and Command Systems Conference, European Space Agency (ESA), June 1998.
20. Law, E. L., ITC-98 Session Chair: xe2x80x9cRCC Alternate Standards and IRIG106 update,xe2x80x9d Briefings by DoD during ITC/USA 98 Internat. Telemetry Conference, San Diego, October 1998.
21. K. Feher: xe2x80x9cFQPSK Doubles Spectral Efficiency of Operational Systems: Advances, Applications, Laboratory and Initial Air to Ground Flight Testsxe2x80x9d, File: ITC.98. Final Paper. Rev. 5. Aug. 14, 1998 (Date of Submission) for publication in the Proc. of the International Telemetering Conference, ITC-98; San Diego, Oct. 26-29, 1998.
22. Simon, M. K, Yan, T. Y. xe2x80x9cPerformance Evaluation and Interpretation of Unfiltered Feher-Patented Quadrature Phase-Shift Keying (FQPSK),xe2x80x9d California Institute of Technology, JPL-NASA publication, TMD Progress Report 42-137, Pasadena, Calif., May 15, 1999.
23. Winters, J. H.: xe2x80x9cAdaptive Antenna Arrays for Wireless Systems,xe2x80x9d Tutorial Notes presented/distributed at the 1999 IEEE Vehicular Technology Conference, Houston, Tex., May 16, 1999.
This invention includes disclosure of new and/original spectral efficient and RF power efficient-high performance technologies, new architectures, embodiments and new Bit Rate Agile (BRA) implementation of 2nd generation FQPSK Transceivers. These inventive structures, methods, and technologies are suitable for a large class of implementations and applications. Numerous embodiments of the inventive structures and methods are enabled. These include cost effective solutions for BRA, Modulation and Demodulation (Modem) Format Selectable (MFS) and Coding Selectable (CS) processors, modulators/demodulators, Transceivers, having agile/tunable RF frequency embodiments and are suitable for power efficient NLA systems.
The terms abbreviations and descriptions used in the 1st generation of Feher et. al inventions, highlighted in the xe2x80x9cBackground of the Inventionxe2x80x9d section, as well as other previously identified terms/acronyms and abbreviation and in particular FQPSK and related terms, used in the cited references, are retained and/or slightly modified and are used relative to this disclosure of the new invention to describe second generation xe2x80x9c2nd generationxe2x80x9d BRA architectures and embodiments of FQPSK, FGMSK and FQAM Transceivers. This disclosure contains embodiments for further significant spectral savings and performance enhancements, and new functions and architectures, which were not, included in the referenced prior art patents, inventions and publications.
BRA or xe2x80x9cBit Rate Agilexe2x80x9d abbreviation and term describes technologies, implementations, embodiments suitable for design, use and applications in which the information rate, source rate, or the often used alternative terms xe2x80x9cbit ratexe2x80x9d, xe2x80x9csymbol ratexe2x80x9d, or xe2x80x9cdata ratexe2x80x9d may be selectable or programmable by the user or by one or more control signal(s). Bit Rate Agile (BRA) systems may be programmable by software or have predetermined or xe2x80x9cselectable,xe2x80x9d i.e., xe2x80x9cagilexe2x80x9d bit rate applications. The term xe2x80x9cbit rate agilityxe2x80x9d refers to variable and/or flexible selectable bit rates (again bit rate, symbol rate, data rate, information rate, source rate, or equivalent); the bit rates could be selected on a continuous fashion in small increments and/or in steps. These systems are designated as BRA (or Bit Rate Agile) systems. BRA, MFS, and CS systems requirements are increasing at a rapid rate.
Changeable (or variable, or selectable) amounts of cross-correlation between Time Constrained Signal (TCS) response processors and/or combined TCS and Long Response (LR) processor and/or post processor filters of in-phase (I) and quadrature (Q) phase signals of BRA Transceivers, MFS and CS baseband signal processing implementations and architectures for tunable RF frequency embodiments having enhanced spectral efficiency and end-to-end performance are disclosed. These new BRA, MFS and CS classes of FQPSK signal processors, modems and transceivers, with Adaptive Antenna Arrays (AAA) and RF power efficient amplifiers and entire Transceivers, operated in fully saturated or NLA mode, with intentionally Mis-Matched (MM) modulation and demodulation filters, transmit BRA and receive BRA filters/processors, disclosed herein, attain high performance advantages and significant spectral savings.
A changeable amount of cross-correlation between the BRA and MFS Time Constrained Signal (TCS) response processor and/or combined TCS and Long Response (LR) processor and/or post processor filters of the transmitter with selectable MM between the BRA transmitter and BRA receiver and CS processors, including single and separate in-phase (I) and quadrature (Q) signal storage/readout generators and single and/or separate I and Q channel D/A architectures and a bank of switchable filters for cross-correlated BRA, MFS and CS formats are also disclosed.
These new classes of 2nd generation of FQPSK signal processors, modems and transceivers, with Adaptive Antenna Arrays (AAA) and RF power efficient amplifiers and entire Transceivers, operated in BRA, MFS and CS fully saturated NLA mode, or with LIN mode with intentionally Miss-Matched (MM) transmit BRA and receive BRA filters/processors, disclosed herein, have robust performance and significant spectral saving advantages.
In addition to digital embodiments, BRA analog cross-correlation implementations and combined digital-analog active and passive processors, for 2nd generation FQPSK Transceivers are also disclosed. Subsets, within the generic 2nd generation of the FQPSK family of processors, modems and transceivers are also designated as 2nd generation BRA Feher""s Minimum Shift Keying (FMSK), Feher""s Gaussian Minimum Shift Keying (FGMSK), Feher""s Frequency Shift Keying (FFSK) and Feher""s Quadrature Amplitude Modulation (FQAM).
Switched BRA, selectable Cross-Correlation (CC or Xcor) transmit and receive bandwidth Mis-Matched (MM) low-pass, band-pass and adaptive filter means and controller circuits and algorithms for preamble contained and differentially encoded and/or Forward Error Correction (FEC) with Redundant and Pseudo-Error (PE) based Non Redundant Detection (NED) implementations for FQPSK are also described.
The term xe2x80x9cMis-Matchedxe2x80x9d (MM) designates an intentional and substantial mis-match (MM) between the bandwidth and/or frequency or phase response of modulator filters and demodulator filters and/or mis-match (MM) between one or more implemented FQPSK filter(s) and the theoretical optimal performance minimum bandwidth Nyquist filters.
The term xe2x80x9cAgile Cascaded Mis-Matchedxe2x80x9d (ACM) designates the BRA and RF agile (xe2x80x9cflexiblexe2x80x9d or xe2x80x9ctunablexe2x80x9d RF frequency) cascaded TCS response and LR processor/filter(s) which are mismatched within their respective application and/or use within this invention.
For NLA and for LIN amplifiers, selectable FQPSK filtering strategies in the transmitter and separately in the receiver lead to further spectral efficiency enhancements. Fast synchronization systems and robust efficient adaptive equalizers/adaptive switched systems are also disclosed.
The inventive structure and method includes transmit elements, receive elements, and transmit and receive elements, and may be applied to a variety of communication applications, including, but not limited to, wireless communications and cellular systems, satellite systems, mobile and telemetry systems, broadcasting systems, cable system, fiber optic systems, and more generally to nearly all communication transmission and/or receiving systems.
In one embodiment of the invention, a bit rate agile communication system is provided and includes a splitter receiving an input signal and splitting the input signal into a plurality of baseband signal streams, and a baseband signal processing network receiving the plurality of baseband signal streams and generating cross-correlated cascaded processed and filtered bit rate agile (BRA) in-phase and quadrature-phase baseband signals. In another embodiment, a quadrature modulator receiving and quadrature modulating the cross-correlated filtered in-phase and quadrature-phase baseband signals to generate a quadrature modulated output signal is also provided. In another embodiment, the baseband signal processing network includes a cross-correlator and at least one bit rate agile cascaded mismatched (ACM) modulator filter.
In yet another embodiment, the invention provides a bit rate agile communication system including a baseband signal processing network receiving parallel baseband signal streams and generating combined Time Constrained Signal (TCS) response and Long Response (LR) filtered in-phase and quadrature-phase baseband signals. In a variation of this embodiment, the inventive structure also includes a quadrature modulator receiving and quadrature modulating the Time Constrained Signal (TCS) response and Long Response (LR) filtered in-phase and quadrature-phase baseband signals to generate a quadrature modulated bit rate agile output signal.
In still another aspect, the invention provides a method for generating bit rate agile signals in a communication system. The method includes the steps of processing a plurality of signal streams to generate cross-correlated signals having changeable amounts of filtering for bit rate agile in-phase and quadrature-phase baseband signals. The inventive method may also include the step of receiving an input signal and converting the input signal into the plurality of signal streams. It may also optionally include the further step of modulating the cross-correlated filtered in-phase and quadrature-phase baseband signals to generate a quadrature modulated bit rate agile output signal.
In yet another aspect, the invention provides a method for generating bit rate agile signals in a signal transmission system, where the method includes the steps of receiving a plurality of signal streams, processing the plurality of signal streams to generate cascaded Time Constrained Signal (TCS) response and Long Response (LR) filtered in-phase and quadrature-phase baseband signals; and modulating the Time Constrained Signal (TCS) response and Long Response (LR) filtered in-phase and quadrature-phase baseband signals to generate a quadrature modulated bit rate agile output signal.